Figures obtained from the Department of Finance by Sinn Fein finance spokesman Pearse Doherty reveal the spending on legal advice by the agency over the last two years.

In 2010, NAMA spent €9.7m on lawyers but that soared to €16.5m last year, as the agency stepped up enforcement activity against developers.

There is no sign of the spending slowing down, with more than €1m already paid over for advice in 2012.

Last night a spokesman for NAMA said money spent on lawyers ended up saving the agency money.

"Arising from these (legal) reviews, questions were raised about the enforceability of security in certain cases and as a result legal discounts amounting to €368m were imposed; this reduced correspondingly the acquisition cost of the loans.

"Therefore, the saving to the State in carrying out this due diligence was a large multiple of the legal costs incurred," the spokesman said.

The level of fees paid will add to concerns that the toxic debt agency will be a bonanza for the same firms of lawyers and professional advisers that benefited during the property boom NAMA was established to unpick.

Legal fees are not even the largest share of NAMA's budget for advisers. Last year the agency paid €73m in fees to banks and outside agencies for the administrative work on NAMA's thousands of individual loans.

One of the most lucrative areas for consultants and accountants is the fee paid for reviewing developer's business plans.